NASA says sea levels will rise by a metre over the next century

NASA’s OMG mission will examine how warm ocean water is speeding the loss of Greenland’s glaciers. PIC: NordForsk

EXPERTS fear an ice sheet the size of Queensland is melting so quickly it will cause massive storm surges capable of decimating Australia’s coastal cities within the next century.

Satellite images recently captured by NASA show large sections of Greenland and Antarctica are vanishing at a much faster rate than previously thought.

Because of this scientists now believe sea levels will rise by a metre over the next 100 to 200 years. And this is not good.

Dr Steve Rintoul from the CSIRO told news.com.au if the NASA predictions prove true Australia could expect more devastating flash floods similar to the one suffered by Brisbane four years ago.

He said as the average sea level rose, so did the risk of destructive storm surges.

“What that means is that the frequency and severity of coastal flooding increases and those floods are more serious as the average sea level rises,” he said. “Most Australians live along the coast, and this is where we are going to feel the impact of sea levels rises.

“There is also about 150 million people that live within one metre of present day sea level, and so if sea levels rise by one metre, those people will be displaced. Many of our major cities around the world are close to sea level and also much of our industry and infrastructure is also close to the coast. The implications of rising sea levels are quite serious because a one metre rise would cause serious disruption not just to people on low level islands but to infrastructure and the economy in countries that have a coastline.”

Dr Rintoul said cities such as Sydney would be partly affected with areas above sea protected from the surges whereas a much lower lying city such as Brisbane would be at greater risk.

Since 1992, the world’s oceans have risen by almost 8cm, and in some places by as much as 23cm.

Most of this extra water has come from melting ice and glaciers.

According to NASA, the Greenland ice sheet has caused the most concern, shedding around 303 gigatons of ice a year over the past decade. The Antarctic ice sheet has lost an average of 118 gigatons a year.

In a bid to prepare the world for this impending doom, NASA has embarked on a new mission - the OMG mission.

Oceans Melting Greenland will map the entire 1.7 million sq km ice sheet, which is the size of Queensland.

It is also about 1.6km deep and contains enough water to raise global sea levels to around six metres if it melts.

The project will examine the role of ocean currents and ocean temperatures in melting Greenland’s ice from below — and try to better predict the speed at which the ice sheet will raise sea level.

Tracking the ice sheets’ disappearance has not been simple in the past.

“In Greenland, everything got warmer at the same time: the air, the ocean surface, the depths of the ocean,” Ian Joughin, a glaciologist at University of Washington, in Seattle said. “We don’t really understand which part of that warming is having the biggest effect on the glaciers.”

Sea floor depths on Greenland’s west coast, measured by sonar aboard a research ship as part of the OMG project. PIC: NASA/JPL-CaltechSource:Supplied

And while Greenland is causing the most concern, scientists are also just as worried about the Antarctic.

Dr Ian Allison from the University of Tasmania told news.com.au there were a few key areas in the region that had a similar problem with warming ocean waters that caused ice shelves to melt and flow into ocean faster.

The glaciers in Amundsen Sea in West Antarctica were last year to be found melting rapidly, leading experts to predict the rest of the area will soon follow.

Warm waters from the Southern Ocean have been reaching the bottom of the West Antarctic Ice Sheet, causing it to melt.

He said there was also an area just east of Casey Station (one of Australia’s research hubs) which was also experiencing a loss of ice.

And while East Antarctica’s massive ice sheet is thought to be at less risk, NASA says recent research found two deep troughs that could lead warm ocean water to the base of the glacier and melt it in a similar way to what’s happening to the glaciers in West Antarctica.

If the experts predictions materialise, Dr Allison said not only will sea levels rise, they will also cause more storms.

“The main problem with sea levels rising is that they will cause more storm surge events and seeing as most of our infrastructure now is along the coast, such as our airports, roads, powerlines, it will affect them,” Dr Allison said. “If sea levels were to go up 50cms there are many parts of the world where a storm surge height that might have only occurred once every hundred years might occur almost weekly.

“It is those statistical events, those surges that will cause the problem similar to the sort of thing you got in New Orleans and the US north-east coast. So it’s just sea levels going up, its when a big storm comes the tides are up and there’s a huge surge.

“For example people are already calculating The Thames barrier which is meant to storm surges from getting up to London that is going to have to be rebuilt in a decade or so.”

Dr Allison said studies such as the one NASA was carrying out at Greenland were vital in trying to prepare civilisation for what lies ahead.

“I think we have known for a while that the ices sheets that contributed to sea level what we haven’t been able to do is very accurately project how we are going to respond in the future,” he said. “So we know what they are doing in the present, but if we keep warming the world how are the ice sheets going to respond and how fast is sea level going to go up. Studies like this are addressing that problem by trying to understand the processes and the vulnerable paths.”